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Acclimatization to neurological decompression sickness in rabbits
Chien-Ling Su1, Chin-Pyng Wu, Shao-Yuan Chen
1Institute of Undersea and Hyperbaric Medicine, National Defense Medical Center, P.O. Box 90048-516, Taipei 114, Taiwan, Republic of China.
Summary
Diving acclimatization may be linked to a stress response. Prior decompression sickness (DCS) exposure in rabbits reduced the severity of neurological DCS in subsequent dives, suggesting a protective preconditioning effect.
Area of Science:
- Physiology
- Marine Biology
- Biomedical Science
Background:
- Diving acclimatization involves reduced susceptibility to decompression sickness (DCS) after repeated dives.
- The mechanism may involve stress preconditioning, similar to that observed in other physiological stresses.
- Previous research suggested a link between acclimatization and stress preconditioning.
Purpose of the Study:
- To investigate the protective effect of prior DCS exposure on neurological DCS severity in rabbits.
- To determine if DCS itself induces a stress response, characterized by heat-shock protein 70 (HSP70) expression.
- To explore the potential of DCS preconditioning as a mechanism for diving acclimatization.
Main Methods:
- Rabbits were exposed to a high-pressure cycle (6 ATA for 90 min) to induce DCS.
- Heat-shock protein 70 (HSP70) expression was measured in tissues of rabbits with and without DCS.
- A separate group of rabbits underwent a second pressure cycle after initial DCS exposure to assess preconditioning effects.
- Neurological scores were used to quantify DCS severity.
Main Results:
- Rabbits experiencing DCS showed increased HSP70 expression in lungs, liver, and heart.
- Initial DCS exposure resulted in a neurological score of 46.5 (SD 19.5).
- Rabbits with prior DCS preconditioning had a significantly lower neurological score (16.3 SD 28.3) after a subsequent pressure exposure compared to those without preconditioning.
Conclusions:
- Decompression sickness (DCS) in rabbits is associated with an increased stress response, indicated by HSP70 expression.
- "DCS preconditioning" attenuates the severity of neurological DCS upon subsequent exposure.
- This stress response and preconditioning effect may explain the physiological basis of diving acclimatization.